Animal movement is driven by both habitat qualities and individual traits. Despite this, few studies assess the relative contributions of movement-related traits and landscape characteristics to movement. We examined the relationship between morphology, habitat characteristics, and matrix resistance in the movements of the cactus bug, Chelinidea vittiger. C. vittiger feeds upon and moves between patches of cactus, is easily photographed for morphological measurements, and can be studied in large numbers at a scale that encompasses both habitat (cactus) and the intervening vegetation matrix. To examine initial dispersal in inexperienced adults, we introduced 400 individuals to native Opuntia humifusa habitat. We selected four 50x50m plots, two each with low and high densities of naturally occurring cactus. Within each plot, we surveyed the vegetation matrix to calculate resistance to movement. We then repeatedly recaptured our marked insects on labeled and mapped patches to monitor movement for a month after release.
Results/Conclusions
We examined the effects of habitat characteristics (patch size and density), matrix resistance, and morphological traits on insect dispersal. Surprisingly, we did not find any effects of matrix resistance on insect movement. Habitat characteristics did impact movement, with the effects of patch size and location modified by patch density. When on a patch surrounded by nearby cactus, insects moved further in low-density plots. This pattern did not occur in high-density plots. C. vittiger were also found in greater abundance near the release point in low-density plots, while more bugs were found on large patches in high-density plots. However, habitat density did not affect the role of morphology in movement: bugs with smaller body and wing area were more likely to move from a patch, regardless of patch density. We conclude that while the effects of patch traits on movement depend on habitat density, morphological traits may function independently of habitat characteristics during initial dispersal.